Self-exciting constant-current alternator



(No Model.) -3 Sheets-Sheet 1.

A. SCHMID & B. G. LAMME.

SELF EXCITING CONSTANT CURRENT ALTERNATOR. No, 550,354. Patented Nov.26, 1895T---- (Cw-[M5565 I M Zlnwnfom I y :4 5: All,

ANDREW IGRAHAM. PHOTO-UTHO.WA5HINFTON, D50.

(No Model.) 3 Sheets-Sheet 2. ,A. SOHMID & B. G. LAMME. SELF EXCITINGCONSTANT CURRENT ALTERNATOR.

No. 550,354. Patented Nov. 25, 1895? Fig.2..

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' SOHMID & B. G. LAMME. SELF EXCITING CONSTANT CURRENT ALTERNATOR No.550,354. Patented Nov. 26, 1895.

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WINESSES: INVENTORJ I M 55 M l w z UNITED STATES PATENT OFFICE.

ALBERT SOHMID, OF ALLEGHENY, AND BENJAMIN G. LAMME, OF PITTSBURG,PENNSYLVANIA.

SELF-EXCITING CONSTANT-CURRENT ALTERNATOR.

SPECIFICATION forming part of Letters Patent No. 550,354, dated November26, 1895.

Application filed August 24, 1891. $erial No. 403,520. (No model.)

T at whom it may concern.-

Be it known that we, ALBERT SOHMID, a citizen of the Republic ofSwitzerland, residing at Allegheny, and BENJAMIN Gr. LAMME,

a citizen of the United States, residing at Pittsburg, in the county ofAllegheny, State of Pennsylvania, have invented a certain new and usefulImprovement in Self-Exciting Alternate Oonstant-CurrentElectric Generarotors, (Case No. 411,) of which the following is a specification.

The invention relates to a method of and apparatus for generating in anelectric circuit alternating electric currents of constant I 5 quantitythroughout variations in the external resistance, and maintaining thefield of force of such generating apparatus by means of currentsdeveloped in the machine itself.

The invention consists, in general terms,

in supplying the field-magnet coils with currents developed in certainsupplementary armature-coils which tend to deliver currents ofincreasing potential when the load upon the generator increases, and inconnecting in z 5 series with these coils other coils in which atendency toward an increasing potential is also developed by incrementsin the amount of work being performed in the armaturecircuit; but theelectromotive forces developed in the two systems of coils oppose sothat there is a resultant electromotive force increasing by the properamount to maintain the requisite field of force for causing the armatureto deliver a constant current to the work-circuit.

The invention relates especially to the class of electric generatorsdescribed in Patent No. 418,659, dated December 31, 1889, and issued to\Villiam Stanley, J r.

The invention will be described more particularly in connection with theaccompanying drawings, in which- Figure 1 is a diagram of the armatureshowing the coils applied thereto. Fig. 2 is a diagram showing therelation of the armature and field-magnet circuits, and Fig. 3 is atheoretical diagram illustrating the relative values of the two systemsof electromotive forces developed in the two circuits.

Referring to the figures, A represents the armature-core, having poles aa a a the. Main armature-coils b 11 &c., are wound, respectively, uponthe poles a to a inclusive, but are so arranged that the coils b b If Uare wound in a given direction upon the alternate poles and the coils bb and b in the opposite direction upon the intervening poles. Thegeneral construction and operation of this armature for maintainingconstant currents is described in the patent above referred to, and theorganization is such that it tends to deliver an approximately constantcurrent under varying loads.

For the purpose of exciting the field-magnet (represented in the diagramat F, Fig. 2) currents continuous in direction are required. For thispurpose coils c are wound upon the pole a, and no main armaturecoils b&c., are wound upon this pole.

In the normal operation of the machine the number of lines of force fromthe field-magnet which would tend to thread the coils 0 would increasesomewhat under increasing loads, and in practice the increase in thedifference of potential due to such increase in the lines of force mightcause the current delivered to the fieldmagnet coils to increase toorapidly as the load increases, so that it would overregulate. Tocompensate for such increase, the supplemental coils o c 0 &c., arewound upon the other poles of the armature, and they are connected inseries with the coils c and wound in such direction that theelectromotive force developed therein will be opposed to that developedin the coils c. This will produce the desired compensation and cause aresultant current to be delivered to the commutator O and through it tothe field-magnet coils f, in value slightly increasing with increasingloads, so that there will be a resultant field force which will increasein value as the electromotive force required at the terminals of themain armature-coils increases by very nearly, if not exactly, the amountrequired to maintain a constant current upon the work-circuit \V. Anadjustable resistance B may be included in the conduotor 0'', leadingfrom the commutator-brush 1) of the commutator C to one terminal of thefield-magnet coils. The successive poles of the field-magnet are ofopposite polarity, as indicated by the winding and by the letters N S.The cond uctor 7 leading from the fieldmagnet coils, is connected withthe brush p of the commutator C. Currents are delivered from thearmature-coils b b to the work-circuit IV through the commutatonbrushesq g In the theoretical diagram, Fig. 3, the relative values of theelectromotive forces are illustrated. The line marked 00 2 is a normal,above which is plotted a curve 0) g, which indicates the value of theelectromotive force developed in the coil 0 during different loads uponthe machine. The curve cow represents the value of the electromotiveforce developed in the supplemental coils c 0 &c., through variations inthe amount of work being done, and the ordinates between the two curvesrep resent the effective electromotive force,being the differencebetween the two electromotive forces, since the electromotive force inthe coils c 0 &c., is opposed to that in the coils c.

It will be noticed that when no work is being done there is still a highelectromotive force developed in the coils c,while no electromotiveforce is developed in the coils c 0 &c. This is due to the fact that thelines of force from the field-magnet tending to thread thearmature-coils Z) 19 are opposed by an approximately equal number oflines of force developed by the magnetic potential due to the currentflowing from the armature-coils through an external circuit of noresistance, so that no lines of force succeed in threading the coils 0 0etc. VVhemhoweveigwork is being done in the work-circuit, the number oflines of force allowed to pass through the armature-poles a to coinclusive, gradually increases, and thus the electromotive force in thecoils 0 0 &c. ,increases accordingly. The electromotive force in thecoils 0, however, i11- creases at a greater rate during such time,especially because of the shifting of the relative time of theappearance of maximum magnetic polarity on the part of the pole-pieces aand its passage across the faces of the pole-pieces of the field-magnet,so that the resultant effective electromotive force may be made toincrease under increasing loads to as great an extent as required forthe automatic regulation of the machine.

It should also be observed that by suitable variations in theproportions of the coils the resultant exciting-current may be made tohave a constant or a decreasing electromotive force, as desired indifferent cases.

I'Vhile the generator above described is primarily intended to be soconstructed that the regulating means employed shall maintain a constantcurrent in the work-circuit, it is to be understood that the severalwindings of the generator may be so proportioned relatively to eachother that the regulating means described and hereinafter claimed mayserve to maintain a constant potential in the workcircuit. IVe thereforedo not desire to limit our invention to the particular function of ourmeans of regulation, whereby mainte nance of a constant current in thework-cin cuit is effected.

WVe claim as our invention 1. The combination with the field magnets ofan electric generator, of an armature having radiating poles, mainarmature coils wound upon certain of the poles and delivering currentsto a work-circuit, field-exciting coils wound upon the remainder of thepoles, a commutator with which the field exciting coils are connected,field magnet coils having circuit connections with the commutator, andopposing supplemental coils wound upon the other poles and connected inseries with the first-named field exciting coils.

2. In an electric generator the combination of the armature core A,having the work cir* cuit coils b, b wound upon certain of its poles,field exciting coils c wound upon the other poles and opposing fieldcoils 0, c &c.,wound upon the same poles with the coils Z), t andconnected in series with the coils c, substan tially as described.

3. In a self-exciting electric generator, the combination of a polararmature having certain of its poles provided with work-circuit coils,other of its poles supplied with field exciting coils, and compensatingor opposing field-exciting coils applied to the first named poles andconnected in series with the fieldexeiting coils, substantially asdescribed.

4:. The combination with the field-exciting coils of an electricgenerator, of compensating or opposing coils on the armature connectedin series therewith and developing a counter potential, substantially asdescribed.

5. In a self-exciting electric generator the combination with anarmature having radiating pole pieces with overhanging lugs, of workcircuit coils placed upon certain of the poles beneath said lugs, fieldexciting coils placed upon other of said poles and means for generatingelectromotive force opposing that developed in the last-named coils, invalue varying with the electromotive force developed in the work-circuitcoils.

6. In a self-exciting electric generator the combination with thework-circuit coils, of coils generating electromotive force increasingin value with increments in the work be ing done, and coils generatingelectromotive force opposed to that developed in the lastnamed coils andalso increasing in value with the increments in the work being done.

7. In a self-exciting electric generator the combination with thework-circuit coils, of main field exciting coils generatingelectromotive force increasing in value with. increments in the Workbeing done, and coils gensubscribed our names this 24th day of Sep-ALBERT 'SOI-IMID. BENJAMIN G. LAMME. \Vitnesses J. W. TATE, Jr., J. W.SMITH.

